1. Field of the Invention
The present invention relates to thermosetting cationic latices, coating compositions prepared therefrom and the process for preparing the same.
2. Brief Description of the Prior Art
Cationic latices are known in the art and their method of preparation involving free radical emulsion polymerization of monomers in water, in the presence of cationic surfactants, is also known. The free radical emulsion polymerization procedure generally results in high molecular weight polymeric products which are normally in the range of 100,000 to several million. In this molecular weight range, the latices possess good mechanical properties. It has, however, been found that the latices leave something to be desired as to film properties relating to protective durability, i.e., the ability of coatings to maintain their integrity against chemicals, weathering, and the like.
In areas such as paper and textile manufacture where protective durability is not an essential service condition, cationic latices in their thermoplastic form have found a ready application primarily due to their inherent adhesion to anionic substrates. In areas such as protective coatings manufacture, where protective durability, particularly outdoor durability, is an essential service condition, the cationic latices in their thermoplastic form are less desirable. In order to prepare good coatings, particularly protective coatings, with properties of outdoor durability, it is desirable to use thermosetting compositions. Coating compositions comprising thermosetting latices are, moreover, advantaged in that their application avoids problems such as air pollution, fire hazards and other problems which attend solvent-based coating compositions. The art-known thermosetting latices of commercial significance are, however, basically anionic, and not cationic.
In developing the present invention, it has been found that there are a number of attendant problems that might have hindered the development of cationic thermosetting latices of commercial significance, particularly for coating applications.
There is now provided by this invention, a thermosetting cationic latex, which is particularly useful in preparing thermosetting coating compositions.